Tuner



Sept. 7, 1948. F. WILBURN 2,448,642

TUNER Filed March 3, 1947 2 Sheets-Sheet 1 22am-f i i i ,7 5726.2 i l i /7' e I ,4 i y A l F Bnventor Sept. 7, 1948. F. wlLBURN 2,448,642

TUNER Filed March 3, 1947 2 Sheets-Sheet 2 e l Gttorncg Patented Sept. 7, 1948 UNITED STATES PATENT oEFlcE Application March 3,(7ej'al7lo, 731,937

2 Claims.

This invention relates generally to ultra highfrequency tuners and oscillators, and may be regarded generally as dealing with improvements in the type of device disclosed in my copending application entitled Ultra high frequency tuner, filed March 4, 1946, Serial No. 651,908.

The device of my said Iprior application provided a pair of relatively rotatable inductor elements forming a pair of coaxial, close-spaced coils of one turn each, which were adapted to be progressively converted from parallel to series connection to increase their inductance, while at the same time the eifective distributed capacity between them was being increased. In one embodiment, the provision for accomplishing this result included a brush carried by one end of one of the coils and arranged for sliding contact with the other of the coils. This device was highly eicient, and had the advantage of an unusually high Q.

Objects of the present invention include the provision of a tuner of the same class, but of greater compactness, and one wherein no sliding contacts are used, with all external connections leading from the stator.

The invention may be discussed to best advantage after referring to the accompanying drawings showing a present illustrative embodiment thereof, and wherein Figures 1 and 2 are diagrammatic views showing the electrical make-up of the device in its two extreme positions of adjustment, Figure 1 being the high frequency position and Figure 2 being the low frequency position;

Figure 3 is an end elevation of a preferred embodiment of the invention;

Figure 4 is a longitudinal vertical section on line 4 -4 of Figure 3;

Figures 5 and 6 are transverse detail sections on lines 5-5 and 8 6, respectively, of Figure 4;

Figure 7 is a detail section on line 1--1 of Figure 3;

Figure 8 is a detail section on broken line .-8 of Figure 3; and

Figure 9 is a detail section on line 9--9 of Figure 6.

In the drawings, and with particular reference at this time to Figures 1 and 2, numeral IB desig nates generally a rotor comprising a one-turn inductor or coil, having a slot or gap at II, while numeral I2 designates generally a stator compris--v ing a two-turn inductor or coil, having an intermediate cross-over point at I3, and its two ends forming a gap I4. The rotor I and stator I2 are coaxially mounted, in relatively close-spaced rela.-

tion, so as to provide capacltative coupling between the rotor and portions of the stator in a manner presently to be described.

The stator I2 may be considered as made up of two sections AB and EF, which are both annularly spaced from rotor I0 by a uniform narrow gap g, and a 360 section CD connected between sections AB and EF. A relatively close distributed capacitative coupling is thus provided between the full length GH of rotor I0 and the two 180 end sections AB and EF of the stator. Suitable physical structure by which such spacial relationships may be obtained will be disclosed hereinafter.

Figure 1 shows the high frequency position of the tuner, and Figure 2, where the rotor has been rotated through 180, the low frequency position thereof. It will be seen that in both positions, the stator provides a coil of -two turns, and that the inductance of the device is xed for all positions. The rotor I0, being arranged throughout its length in close proximity to longitudinal sections of the stator coil, and being therefore capacitatively coupled thereto, greatly augments the distributed capacitance of the combination. Although the actual capacitance between the stator and rotor remains approximately constant for all positions of the rotor, its distribution along the inductance is varied with change in position of the rotor, causing a change in resonant frequency. In the high frequency position of Figure 1, where the gap in the rotor is alined with the gap in the stator, the distributed capacitance provided by the rotor might be considered as being, in eifect, across but one turn of the stator; While in the low frequency -position of Figure 2, where the gap in the rotor is opposite the cross-over point of the stator, the distributed capacitance provided by the rotor is, in effect, across the full two turns of the stator.

'Ihe device can readily be designed to any working range within the field of about '15 m. c. to 1000 m. c.,and is capable of approximately a 15 percent or greater working range or swing within that field.

Figures 3 to 9, to which reference is now directed. show one present illustrative physical ernbodiment of the invention. Numeral 20 designates a rotor shaft, on which is mounted the aforementioned'rotor I0, and numeral 2i designates an externally threaded bushing which journals an intermediate portion of rotor shaft 20, and which carries the aforementioned stator I2;

One end portion 22 of rotor shaft 20 projects from bushing 2i and is adapted to receive any plate 21, preferably formed of ceramic, and t0 which is secured the rotor I0. The rotor I is in the form of a radially slotted or split washer or annulus 28, the radial slot being indicated again by the numeral il. This annulus 28 is secured to insulation plate 21 by means of screws 29 (Fig. 9), and is preferably spaced from plate 21 lby means of washers 30.

Bushing 2| has at its end adjacent nut 25 an enlarged head or flange 3-2, which abuts a washer 33 positioned on shaft 2@ against screw 25, while a. snap ring 34 snapped into shaft groove 35 adjacent the other end of bushing 2i engages the latter to secure it against axial displacement on the shaft.

Positioned between bushing head 32 and a washer iii backed up by a nut 39 on the bushing is an insulation plate (lil, similar to insulation plate 21, and the elements making up the aforementioned stator are secured to this plate as presently to be described.

The stator includes a washer or annulus 61d, of the same inside and outside diameter as the aforementioned rotor washer 28, and which is secured directly to plate 430 by means of screws S5 (Fig. f3). It will later become evident that this stator member M corresponds, electrically, to the turn or coil CD of Figs. 1 and 2. This annulus 44 is split at the bottom by a gap et (Fig. 3) which is so shaped as to form two horizontally extending, vertically spaced end portions 41 and 48 which overlap one another as indicated. The gap 46 may be described as having a horizontal chordal portion 46a, and vertical portions 46h and (itc extending upwardly and downwardly, respectively, from opposite ends of the portion 46a..

The stator includes also, in correspondence to half-turn coil portions AB and m' of Figures 1 and 2, two arcuate, substantially 180 washer segments and 5i (Figure 5), these having the same inside and voutside radii as the aforementioned rotor and stator annuli 29 and dii. Members 50 and 5i are spaced at the top to form the gap i4, and they are also spaced at the bottom, as indicated at 52, though no electrical gap is formedV thereby. Terminal portion (il of stator ring d4 will be seen from Figures 3 and 8 to overlap a portion of stator member 5i, and connection is made therebetween by means of screw 43 and spacer sleeve 54. Similarly, terminal portion 48 of stator ring 4t overlapsa portion of stator member 50, and connection is made therebetween by means of screw and spacer sleeve 56. The lower ends of members 50 and 5i are thus mounted on the two end portions of ring 44, in a cross-over" relationship, effecting the electrical cross-over i3 of Figures 1 and 2.

The upper ends of arcuate members 50 and 5I are mounted on but insulated from the upper portion of stator ring 44. As appears in Figure '7, a mounting screw 60 passes through an enlarged hole in ring 44 and its end screws into plate 5I, suitable insulation washers 6i and 62 serving to space the parts properly. Terminal lugs 65 and 66 are secured between the stator 4 plates 50 aid 5I and the washers 8i, and serve as the end terminals of the coil. A third, middle terminal lug 51 is secured to the top of ring 44, and serves as a center connection to the coil.

The device of Figures 3-9 carries into practical eil'cct the electrical features of the tuner of Figures 1 and 2. It should be clear that the split rotor washer 28 corresponds to the one-turn rotor coil I0 of Figure 1, and that 4the stator I2 of 4Figures 3-9 forms a two-turn c oil like the coil ABCDEF of Figures 1 and 2. Thus starting with .terminal lug 65 (Figure 5) the stator begins with half-turn segment 5I, then crosses the space between the plane of stator members 50 and 5| and that of 360 stator annulus 44 to the terminal portion 4 1 of the latter, continues for a full turn around said annulus, then crosses back to the plane of members 50 and 5I to the corresponding end portion of member 50, and finishes with the half-turn furnished by member 50 to' terminal lug 66. Members 50 and 5I are closecoupled to the rotor, like sections AB and EF, while member 44 is relatively remote from the rotor, like section CD. The stator coil thus has two turns, with its first and last half-tum portions close coupled to the rotor. Suilicient has been said of operation in connection with Figs. 1 and 2, and a repetition is not believed necessary.

To give an idea of typical scale (but without intention of limiting the invention), a tuner constructed in accordance with Figures 3-9 designed for the amateur 144-148 m. c. band has an outside rotor and stator diameter of 2".

The use of a tuner of the present type will be evident to those' skilled in the art, and little need be said in that connection. As a Wave meter, it requires no external connections, even to its statorv In various other uses, e. g., oscillator, superregenerative receiver, crystal rectifier, etc., the three terminal lugs 65, 66 and 61 furnish end and center tap connections to the stator coil. In Figs. 1 and 2, these points are at A, F and M, respectively. In the use of the tuner in a superregenerative receiver, the two terminals A and F would be connected to the grid and anode circuits of the receiver tube, with the center tap M connected through a high pass condenser vto the cathode ofthe tube, in a conventional circuiting arrangement.

The device of the present invention has the advantage of compactness, elimination of sliding contacts. substantial working range between minimum and maximum resonant frequencies, and high Q I claim:A

1. A tuner embodying a pair of coaxial coils, one of substantially one turn and one of substantially two turns, arranged for relative rotation on their common axis; said one-turn coil comprising a substantially 360 ring in a plane at right angles to the coil axis, said ring having a split forming an air gap therein; said two-turn coil comprising a substantially 360 ring in a plane parallel to the rst mentioned plane, said ring being slotted to form two end portions, and two substantially 180 ring segments in a third plane parallel to the other two planes and closespaced to the ilrst mentioned plane, said ring segments being arranged with gaps between opposed ends thereof', andl cross-over connections between the end portions of the 360 ring portion of the two-turn coil and the adjacent ends of the 180 ring segments.

2. A tuner embodying a'pair of coaxial coils, one of substantially one. turn and one of subranged with gaps between opposed ends thereof,-

with one of said gaps so disposed relative to said overlapping ring end portions that each of said 15 2,422,995

ring end portions crosses said one gap and overlaps an end portion of the ring segment therebeyond, 'and electrical connectors between each of -said ring end portions and the said ring seg- 5 ment end portion which it overlaps.

FRANK VVILBRN.

REFERENCES CITED The following references are of record in the 10 flle of this patent:

UNITED STATES PATENTS Name Date Summerhayes Feb. 8, 1944 Vorie June 24, 1947 Number 

